1. Field of the Invention
The invention relates to light guides in general, more particularly to rigid fiber optic light guides having optical elements made of highly transparent plastic molded thereto, and to applications thereof.
2. Description of Related Art
Rigid fiber optic light guides are known from prior art in the form of dental light guide rods. They are usually made by drawing glass rods or a bundle of core-cladding rods. They may be overmolded with a plastic, inter alia, as a sleeve. The plastic material used for this purpose is a black opaque, usually glass fiber reinforced PPS plastic (e.g. FORTRON® by TICONA). Such mounting sleeves are used for accommodating the dental light guide rod in a close fit in a handpiece that comprises the light source.
These sleeves are enclosing portions of the outer circumferential surface of the light guide, the end face of the light guide made of glass is exposed. The emission profile of the electromagnetic radiation guided in the light guide is therefore mainly determined by the geometry and refractive index of the glass of the light guide. If different emission profiles are required, for example in order to achieve additional focusing and/or homogenization of the light, further optical systems will be needed, which have to be attached to the light guide. In particular for medical or cosmetic applications the problem arises that the light guide must be hygienically cleanable and therefore must be capable of being sterilized and/or autoclaved. With prior art lens systems which include lens frames, lens cementing and seats for mounting on the light guide this requirement cannot be met or only with very great expenditure.
DE 10 2012 100 375 A1 discloses a light guide whose optical properties are adjusted by employing liquid polymers. In particular, over the light exit surface a region with these liquid polymers can be located, which are enclosed by a sealing cap. For such a light guide it will be difficult to resist mechanical stresses, in particular because if the sealing cap is pulled off the liquid polymers may leak.